Dumbledore's Magnaminity - Genetics

[Steve]

No: HPFGUIDX 143139

--- In HPforGrownups at yahoogroups.com, "PJ" <midnightowl6 at h...> wrote:
>
> > Roberta:
> > ...right after the "Knew" bit you  quote above, she says 
> > something like:  "How could you be anything  else, my dratted 
> > sister being what she was?" In other words, *that's* how she 
> > "knew."  Her dratted sister was a witch, so of course Harry 
> > would turn out to be a wizard.
> 
> PJ:
> ...edited...
> 
> As it's been explained to us, magic in Muggles isn't like 
> inheriting eye color. It doesn't necessarily follow a hereditary 
> pattern but bounces around a family gene pool.  For instance, 
> the Evans' family were quite ordinary muggles yet Lily, out of 
> nowhere, is a witch. ...edited... Magic in Muggles does not 
> follow a line of heredity and therefore can not be predicted. 
> 
> So even though Harry was Lily's son, there would be little 
> reason for Petunia to "KNOW" or really even *strongly assume* 
> that Harry would be a wizard ... edited.... 
>
> So no... as I see it anyway, Petunia and Vernon could not have 
> *known* (and they were very forceful about *knowing* not just 
> *assuming*) Harry was a wizard simply because of who his parents 
> were.  Dumbledore had to have made it clear what Harry was in 
> that letter...
> 
> PJ

bboyminn:

While I think you have a valid point, I think you are overstating and
overemphasizing certain aspects of it. While it is true that magical
parents is no guarantee of a magical child, it is the norm. Magical
parents are VERY likely to have magical children. That would be the
most common and likely occurance. That said, I will acknowledge that
it is somewhat rare for muggles to have magical children, but it is
even /more/ rare for magical people to have non-magical children. So,
while your points are true, I think you overstated the degree to which
they impact the world.

So, it is very logical and reasonable, and the most commonly occuring
case, that magical parents have magical kids. That makes it perfectly
logical for Petunia to /assume/ that Harry is magical, and that Dudley
is not. Yes, there is an element of uncertainty in both, but the odds
are very much in favor of the common assumption. 

So, one could say that Petunia /knew/ Harry was a wizard with a
reasonable degree of likelihood and certainty, but at the same time,
you are right, she couldn't accurately state it as an absolute fact.

Now, if we want to dabble in the realm of pure speculation, we can, as
I have done many times, speculate the Petunia received her Hogwarts
letter first and that she turned down the opportunity thinking
witchcraft an inappropriate endeavor for a proper young lady. That
would increase the odds of Dudley having magical ability, but of
course, it certainly doesn't guarantee it. 

Further, JKR has said, to the effect, that there is no significants to
Dudley, but she has also said (paraphrased) that we should keep our
eye on Petunia. That there is more to Petunia than meets the eye
(again paraphrased).

Not sure what that adds to the discussion, but there it is.

Steve/bboyminn